1. Field of the Invention
The present invention relates to a liquid container equipped with a piezoelectric apparatus therein which detects the consumption state of liquid inside a liquid container which houses the liquid. More particularly, the present invention relates to the liquid container equipped with a piezoelectric apparatus that detects liquid consumption status in a liquid container which provides liquid to a recording head of an ink-jet recording apparatus.
2. Description of the Related Art
An ink cartridge mounted on an ink-jet type recording apparatus is taken as an example of a liquid container and is described below. In general, an ink-jet recording apparatus comprises: a carriage equipped with an ink-jet type recording head comprised of a pressure generating means which compresses a pressure generating chamber and a nozzle opening which discharges the compressed ink from a nozzle opening in the form of ink droplets; and an ink tank which houses ink supplied to the recording head through a passage, and is structured such that the printing operation can be performed continuously. In general, the ink tank is structured as a cartridge that can be detached from the recording apparatus, so that a user can easily replace it at the time when the ink is used up.
Conventionally, as a method of controlling the ink consumption of the ink cartridge, a method is known of controlling the ink consumption by means of a calculation in which the counted number of ink droplets discharged by the recording head and the amount of ink sucked in a maintenance process of the printing head are integrated by software, and another method of controlling the ink consumption in which the time at which the ink is actually consumed is detected by directly mounting to the ink cartridge two electrodes for use in detecting the liquid surface, and so forth.
However, in the calculation-based method of controlling the ink consumption by integrating the discharged number of ink droplets and the amount of ink or the like by the software, the pressure inside the ink cartridge and the viscosity of the ink change depending on usage environment such as ambient temperature and humidity, elapsed time after an ink cartridge has been opened for use, and usage frequency at a user side. Thus, a problem is caused where a considerable error occurs between the calculated ink consumption and the actual ink consumption. Moreover, another problem is caused in which the actual amount of ink remaining is not known because once the same cartridge is removed and then mounted again, the integrated counted value is reset.
On the other hand, in the method of controlling by electrodes the time at which the ink is consumed, the remaining amount of ink can be controlled with high reliability since the actual ink consumption can be detected at one point. However, in order that the liquid surface of the ink can be detected, the ink need be conductive, so suitable types of ink for use are very limited. Moreover, a problem is caused in that a fluid-tight structure between the electrodes and the cartridge might be complicated. Moreover, since precious metal is usually used as the electrode material, which is highly conductive and erosive, manufacturing costs of the ink cartridge increases thereby. Moreover, since it is necessary to attach the two electrodes to two separate positions of the ink cartridge, the manufacturing process increases, thus causing a problem which increases the manufacturing costs.
Moreover, when managing the ink consumption status by mounting a piezoelectric device on the ink cartridge, ink inside the ink cartridge may roll or bubble by the scanning of the ink cartridge during the printing operation. By the waving or bubbling of ink nearby the piezoelectric device, ink or bubble of ink attaches to the piezoelectric device. Then, there is a cases arises that the piezoelectric device cannot detect the ink consumption quantity by the ink or bubble of ink attached to the piezoelectric device. In other words, even there is only small amount of ink inside the ink cartridge, if the ink attaches to the piezoelectric device mistakenly by the waving of ink, there is a danger that the piezoelectric device detects mistakenly that there is still enough ink inside the ink cartridge. Moreover, if the bubble attaches to the piezoelectric device, there is danger that the piezoelectric device detects mistakenly that there is no ink inside the ink cartridge even if the ink cartridge 180 is filled by ink.
Furthermore, there is problem that the position of mounting the piezoelectric device on the ink cartridge is limited for detecting the ink end status inside the ink cartridge. For example, if mounting the piezoelectric device on the wall at the lower side of the ink surface, the piezoelectric device can detect the ink end. On the other hand, if mounting the piezoelectric device on the wall at the upper side of the ink surface, the piezoelectric device cannot detect the ink end.